Submarine reconfigurable optical add/drop multiplexer with passive branching unit

Abstract

Systems and methods for data transport, including submarine reconfigurable optical add/drop multiplexers, branching units configured to receive signals from trunk terminals (TTs), and dummy light filters configured to pass useful signals through the filters, and to reflect dummy light. Optical interleavers are configured to separate useful signals into two or more groups of optical channels, and the optical channels are set to a frequency of either a left or a right portion of a total channel bandwidth. De-interleavers merge signal groups together from trunk terminals, and lasers at each of the transponders at the source terminals are configured to adjust a destination of a channel by fine tuning a frequency or wavelength of the one or more signals.

What is claimed is: 
     
       1. A method for data transport using one or more submarine reconfigurable optical add/drop multiplexing systems, comprising:
 wherein the optical spectrum is separated into a wavelength division multiplexed (WDM) signal spectrum for WDM signals, and a loading light spectrum, and wherein the WDM signal spectrum is alternating odd and even channels; 
 tuning a laser wavelength at the transmitter at a trunk terminal between odd wavelengths and even wavelengths according to a respective target destination; 
 within a branching unit, passively directing with three interleavers, one for each trunk terminal, and three de-interleavers, one for each trunk terminal, each channel to the respective target destination; 
 interconnecting the three interleavers and the three de-interleavers in a configuration that the two output ports of the interleaver for each trunk terminal are respectively connected to an input port of the de-interleavers for the other two trunk terminals; 
 using optical band pass filters to separate and combine signals at the WDM signal spectrum and the signals at the loading light spectrum; 
 setting loading light at each trunk terminal to maintain power balance for all paths from a source terminal to the branching unit; 
 recycling the loading light at the branching unit for the path from the branching unit to a destination terminal; and 
 at the destination terminal, receiving signals from one or more terminals combined by the de-interleavers at the branching unit. 
 
     
     
       2. The method as recited in  claim 1 , wherein the one or more submarine reconfigurable optical add/drop multiplexing systems include a passive branching unit. 
     
     
       3. The method as recited in  claim 1 , wherein the signals are wavelength-division multiplexed signals. 
     
     
       4. The method as recited in  claim 1 , wherein the three interleavers are 1:2 optical interleavers. 
     
     
       5. The method as recited in  claim 1 , wherein there is zero power consumption at the branching unit. 
     
     
       6. The method as recited in  claim 1 , wherein only a single fiber pair is employed for a branch link at the branching unit. 
     
     
       7. The method as recited in  claim 1 , wherein all channels are fully reconfigurable, thereby delivering 2 K  configurations for each of the one or more source terminals, where K is a total number of the one or more optical channels. 
     
     
       8. The method as recited in  claim 1 , wherein the two or more groups of optical channels include odd and even groups. 
     
     
       9. A system for data transport, comprising:
 one or more submarine reconfigurable optical add/drop multiplexing systems, the one or more systems separating the optical spectrum into a wavelength division multiplexed (WDM) signal spectrum for WDM) signal, and a loading light spectrum, wherein the WDM signal spectrum is alternating odd and even channels, the one or more systems comprising:
 one or more lasers at each of one or more transponders at a trunk terminal configured to tune a laser wavelength at the trunk terminal between odd wavelengths and even wavelengths according to a respective target destination; 
 a branching unit configured to passively direct each channel to the respective target destination using three interleavers, one for each trunk terminal, and three de-interleavers, one for each trunk terminal, located within the branching unit,
 wherein the three interleavers and the three de-interleavers are interconnected in a configuration that the two output ports of the interleaver for each trunk terminal are respectively connected to an input port of the de-interleavers for the other two trunk terminals; and 
 
 one or more optical pass band filters configured to separate and combine signals at the WDM signal spectrum and signals at the loading light spectrum,
 wherein loading light is set at each trunk terminal to maintain power balance for all paths from a source terminal to the branching unit; 
 wherein the loading light is recycled at the branching unit for a path from the branching unit to a destination terminal; and 
 wherein signals from one or more terminals combined by the de-interleavers at the branching unit are received at the destination terminal. 
 
 
 
     
     
       10. The system as recited in  claim 9 , wherein the one or more submarine reconfigurable optical add/drop multiplexing systems include one or more passive branching units. 
     
     
       11. The system as recited in  claim 9 , wherein the signals are wavelength-division multiplexed signals. 
     
     
       12. The system as recited in  claim 9 , wherein the three interleavers are 1:2 optical interleavers. 
     
     
       13. The system as recited in  claim 9 , wherein there is zero power consumption at the branching unit. 
     
     
       14. The system as recited in  claim 9 , wherein only a single fiber pair is employed for a branch link at the branching unit. 
     
     
       15. The system as recited in  claim 9 , wherein all channels are fully reconfigurable, thereby delivering 2 K  configurations for each of the one or more source terminals, where K is a total number of the one or more optical channels. 
     
     
       16. The system as recited in  claim 9 , wherein the two or more groups of optical channels include odd and even groups. 
     
     
       17. A method for data transport using one or more submarine reconfigurable optical add/drop multiplexing systems, comprising:
 wherein the optical spectrum is separated into a wavelength division multiplexed (WDM) signal spectrum for WDM signals, and a loading light spectrum, and wherein the WDM signal spectrum is alternating odd and even channels; 
 tuning a laser wavelength at the transmitter at a trunk terminal between odd wavelengths and even wavelengths according to a respective target destination; 
 passively directing with one or more interleavers inside a branching unit each channel to the respective target destination; 
 interconnecting an interleaver, a de-interleaver, and two cyclic interleavers in a configuration such that two outputs of an interleaver for the trunk terminal are connected to an input port of a respective cyclic interleaver, and two inputs of a de-interleaver for the trunk terminal are connected to an output port of a respective cyclic interleaver; 
 using optical band pass filters to separate and combine signals at the WDM signal spectrum and the signals at the loading light spectrum; 
 setting loading light at each trunk terminal to maintain power balance for all paths from a source terminal to the branching unit; 
 recycling the loading light at the branching unit for the path from the branching unit to a destination terminal; and 
 at the destination terminal, receiving signals from one or more terminals combined by the de-interleavers at the branching unit.